Typically, cooking recipes define a cooking cycle in terms of two variables--time and temperature. However, it is not unusual for recommended times and temperatures to be modified or tuned by individuals based on personal experience. Such modification or tuning is to be expected since any time-temperature relationship will be a function of several other product based factors, e.g. the initial temperature of the food, the amount of the food, the water content of the food, the initial temperature of the cooking appliance, the rate at which the cooking appliance can supply heat, etc.
Variations in the above factors will produce temperature changes during a cooking cycle different from the temperature changes anticipated in an established time-temperature cooking relationship. Within a limited range or bandwidth, such variations in temperature may be compensated for by changing the cooking time. In addition, consistency in cooking will also depend on the ability of the cooking appliance to precisely detect and control temperature.
Microprocessor based oil fryer controls which change cooking time as a function of variations in temperature during a cooking process have been part of the literature for years. For example, U.S. Pat. No. 4,636,949 issued to C. R. Longabaugh for Method and Apparatus for Controlling Cooking Cycles in a Cooking System discloses a control in which a plurality of complex cooking cycles may be programmed. Each cooking cycle may have up to eight combinations of time and temperature set points that describe a unique time-temperature profile for that cycle. In addition, the operator may define an alternate set point to change the time or final temperature of a cooking cycle. Finally, the heater elements are divided into two groups so that when the oil temperature approaches the desired set point, one heater element may be deenergized, and the set point achieved with the application of less heat thereby reducing temperature overshoot.
In addition to the above, there are a large number of other cooking time adjustment philosophies. Further, there are a number of cooking temperature controls which are improvements over the typical on/off temperature control. For purposes of this description, on/off temperature control is effected by cycling a heater on at full power and off depending on whether oil temperature is below or above, respectively, a predetermined temperature. Such temperature control is effective to quickly raise the oil temperature to a predetermined value, but it has an inherent problem of temperature overshoot which results in an undesirably high temperature. The improved temperature controls provide various techniques for minimizing or eliminating overshoot and adjusting power to the oil heater in a temperature bandwidth below the predetermined temperature.
While a purported advantage, the requirement of defining a cooking curve for each cooking cycle may be also viewed as a disadvantage. Further, even though the ability to control two sets of oil heater elements provides some control over temperature overshoot, it is a very imprecise control. Applicants believe that the above control mechanism may be simplified without losing cooking quality.